Pencil first, then ink if I have time. I'm getting better at going straight to ink for the detail work, but for gross body positioning I still need the pencil.
Two seats down from me was someone doing pictures twice as good as this one directly with a fountain pen. I am in awe.
A cool exercise we used to do in art school was to draw a subject for 5 minutes or so without looking at the drawing or picking up our drawing implement. It really helps with breaking down the subject matter into shapes/lines.
Not saying you studied in Korea. But back when I kept an art instagram account I followed a lot of accounts that posted figure drawing. It seems that Korea has a really strong community of figure drawers, a bunch of accounts I followed were from there. And I saw a few post drawings using that exact technique you explained.